Organic thin film transistors (OTFTs) are used in flexible displays such as liquid crystal display devices, organic electroluminescent devices and inorganic electroluminescent devices. Typically, the OTFTs in such devices are used as switching devices that control the operation of each pixel and as driving devices that drive the pixels. Moreover, OTFTs are also used in radio frequency identification (RFID) circuitry, smart cards and sensing devices.
An OTFT typically includes a semiconductor layer having source and drain regions and a channel region, a gate electrode insulated from the semiconductor layer and located in a region corresponding to the channel region. The OTFT also includes source and drain electrodes respectively contacting the source and drain regions.
Currently, OTFTs are fabricated using techniques such as lithography, spin coating and evaporation. Other techniques for forming the OTFTs include printing techniques such as inkjet printing, flexographic printing, gravure printing, offset printing and screen printing. However, it is difficult to control a channel length of the OTFTs formed using such printing techniques. Moreover, certain techniques require additional steps of substrate patterning to control the channel length thereby leading to substantial manufacturing costs.